Combined television and audio broadcasting



F. SCHROTER 2,078,459

COMBINED TELEVISION AND AUDIO BROADCASTING Filed Dec. 5, 1928 INVENTQR FRITZ SCHROETER Patented Apr. 2 7, 1937 PATENT OFFICE COMBINED TELEVISION. AND AUDIO BROADCASTING Fritz Schrtiter, Berlin, Germany, assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphic m. b. 11., Berlin, Germany, a corporation of Germany Application December 5, 1928, Serial No. 323,837 InGermany December 12, 1927 1 Claim.

The object of this invention is to provide an improved means and method for simultaneous broadcasting of visible and audible actions;

More particularly, it is the object of this invention to realize in television broadcasting a perfectly naturaland faithful effect of simultaneous hearing and seeing.

It is a further object of this invention to simplify the methods of television broadcasting in combination with audio broadcasting to a very simplified technical form. It has been suggested to, send out, by the way of broadcasting'and' by :theuse of television apparatus, pictures which can. be made directly perceptible to the eye and sounds which may directly affect theear. As an intermediate step it has been contemplated to confine television broadcasting jto broadcasting from negative pictures, ormore particularly, a moving" picture film for the purpose of red'ucingthe technical difficulties of the problem. It is tobe understood that the exploration bythe aid of a photoelectric cell, whenusing a negative or film permeable to light rays, gives a far stronger initial current than can be'obtained when the object to be transmitted by television is itself illuminated point by point in space, so that only the reflected light can be utilized in the photoelectric cell. This is the object of this invention and results in the elimination of some of the difiiculties associatedwith the problem of amplification.

In carrying out this invention, a moving picture film is taken of the object or action which it is desired to transmit by television by the use of the ordinary photographic processes and at the same time on the same film or upon'another film running in synchronism with the motion picture film, the speech or music is simultaneously recorded in accordance with well known sound recording methods. Thus, the two actions, visible and audible, which are to be transmitted over a greater or less distance are held in a sort of an intermediate recording or clich. Later the optical part of the recording or clich in the form of a transparent film is explored by the aid of a powerful light ray which results in the incidental elimination of some of the amplifier and other technical difficulties for the photo-electric control of modulation of the transmitter apparatus. The reproduction of the acoustic record does not result in any technical difiiculties. In broadcasting both the optical as well as the acoustic, speech or music are thus transmitted from the intermediate recording or clich. This may be effected by the use of dif-. ferent transmitters, though fundamentally 'one and the same carrier .wave may be employed, and therefore, one and the same transmitter by means of double modulation, by means ofwhich the frequency bands corresponding to acoustic and optical transmission are separated. The intermediate recording or clich for the acoustic part may consist of any carrier or vehicle suited for taking and retaining sound impressions in addition to a film strip. Such carriers may consist of any of the well known sound recording carriers such as a wax plate'or disc, steel wire, etc. In the case of an intermediate recording or clich of the latter type for the acoustic part of the transmission, some well known means'must be used to synchronize the intermediate recording or clich with the optical film. The method embodied in this invention not only renders the television work easier in practice but also makes it more expressive. For instance, if some famous persons picture or actions are to be broadcasted together with the speech'or vocal productions, it was possible previously under conditions favorable as regards time and place to make both the optical and acoustic records or clichs to retouch them subsequently if desired, or to change them by ways and means well known in the moving picture art, and to use the form of record that has been accepted as the best at a later time for the control of the broadcast transmitter or transmitters.

Having thus briefly described my invention, attention is invited to the accompanying drawing, in which,

Fig. l is a diagram of the invention showing the relationship of the optical and acoustic reproducing apparatus;

Fig. 2 is a schematic diagram showing more in detail the relationship of the optical and acoustic apparatus and their relationship to the radio transmitters; and

Fig. 3 shows a modification of the system set forth by Fig. 2, and illustrates an arrangement whereby both optical and acoustic signal representations may be transmitted from the same transmitter.

Referring now more particularly to the figures, 9 shows a film or clich which has been prepared similarly to the ordinary talking motion picture film and consists of the two parts: I, the optical record or motion picture portion, and 2, the acoustic record corresponding to the picture portion. The corresponding devices of optic and acoustic records are so arranged that reproduction of the two components may take place by means of apparatus arranged one alongside the other. The film record which moves in the direction indicated by the arrow in Fig. 1 passes first through a device reproducing the acoustic component indicated at 3 and the details of which are shown in Fig. 2 and will be described hereinafter. In its forward travel the film reaches the scanning device for the reproduction of the optical image. The scanning devices comprising the scanning disc 4 rotating at high velocity and carried by the shaft 5. The'scannin disc has at its edge a plurality of uniformly spaced slots 6, the distance from each other of which corresponds approximately to the width of the film record covered by the optical image. These slots 6 revolve past a narrow slit 1 through which a beam of bright light, from the source I! of Fig. 2 and condensed by the lenses l8 and I9, falls upon the photo-electric cell 8. In this manner the optical image during the continuous motion of the film of record is scanned or subdivided into individual lines and it is only necessary that the speed of rotation of the disc and the rate of forward travel of the film record bear a certain relation to one another.

Fig. 2 shows this arrangement more in detail. The film record 9 is passed in any well known manner by means of the perforations in the said film over the sprockets It). For the reproduction of the acoustic part of the record, there is provided a source of light II which serves by means of the lenses I2 and I3 to project the image of the acoustic tone photo-record upon an adjustable slit l4. Behind this slit is a photoelectric cell l5, the current variations in which, caused by the passage of the film record in front of the slit l4, modulate the radio transmitter IS in a well known manner. It is to be understood, of course, that only the acoustic part of the film is projected upon the slit I l. The film after passing the acoustic reproducer passes the optical reproducer as described above and the currentfluctuations caused in the photo-electric cell 8 by the light passing through the scanning disc owing to the varying transparency of the optical film record, is used to modulate the radio transmitter 20 in the usual and well known manner.

Thus, the talking moving picture film or intermediate record or clich may be utilized to simultaneously transmit television and acoustic broadcasting.

By Fig. 3 a modification of the arrangement shown by Fig. 2 has been illustrated, and according to the showing of Fig. .3 the arrangement of the light translating systems is identical except for the fact that the output of the photo cells 8 and I for the optical and acoustic signal representations are connected with appropriate amplifiers 2| and 22 respectively, and these are both arranged to feed their output into a single modulator and transmitter 23, so that the signals may be transmitted from a single transmitting. system.

Having thus fully described my invention, it is to be understood that I do not wish to have myself limited to the form and description of invention herein contained for purposes of illustration only, but rather by the scope of the said invention as set forth in the appended claim:-

I claim:

Apparatus for the simultaneous transmission of television and related and synchronized sound, which comprises, in connection with a moving picture record having a series of pictures taken at uniformly spaced time intervals and a continuous record of a related sound accompaniment forming a. separate part of the record, means for producing anelectrical current, means for modulating said electrical current in 7 accordance with. varying light intensities caused by scanning thepicture portion of said motion picture film record to transmit television, and means for modulating said current in accordance with the recorded and related sound to produce an accompanying sound signal.

FRITZ sCHRoTER. 

